Question: Determine where $f(x)$ intersects the $x$ -axis. $f(x) = (x + 1)^2 - 9$
Answer: The function intersects the $x$ -axis where $f(x) = 0$ , so solve the equation: $ (x + 1)^2 - 9 = 0$ Add $9$ to both sides so we can start isolating $x$ on the left: $ (x + 1)^2 = 9$ Take the square root of both sides to get rid of the exponent. $ \sqrt{(x + 1)^2} = \pm \sqrt{9}$ Be sure to consider both positive and negative $3$ , since squaring either one results in $9$ $ x + 1 = \pm 3$ Subtract $1$ from both sides to isolate $x$ on the left: $ x = -1 \pm 3$ Add and subtract $3$ to find the two possible solutions: $ x = 2 \text{or} x = -4$